Figure 16 - Learn Mode Performance - DCS 992 User Manual

dCS 992 User Manual
dCS Ltd
Synchronising to source, PLL
Learn Mode
Manual part no: DOC063992 iss 2A1
Contact on + 44 1799 531 999
dCS
(inside the UK replace + 44 with 0)
The calibration accuracy is guaranteed for 6 months. Crystals do age, and
although we burn them in, they can still drift with time. In general, the amount
crystals age decreases with time.
The TCXO frequency can be trimmed by using the
(see Offst – VCXO Frequency Trim
adjustable
Pull-in range
PLL Bandwidth
The PLL is very robust, and will lock to very poor signals if necessary. An
External Reference should be a very accurate, very clean signal, of course ...
Typical performance is shown below. A unit was left to learn, foor about an hour,
and then the reference removed. The scope has been left recording the
reference and the dCS 992 output, over a period of half an hour. The dCS 992
has changed in phase relative to the reference less than 3 usecs – so the
learning and subsequent temperature compensation was accurate to about
0.002 ppm.
Figure 16 – Learn mode performance
on page 20). Each TCXO is independently
x
± 300 ppm about nominal frequency
adjustable in factors of two with the remote from
7.8 mHz to 2 Hz
x
Page 45
Manual for Software Version 2.0x
January 2001
Offset
function in the menu
file 063992ma2a1.pdf available from website
email to: more@dcsltd.co.uk
web site: www.dcsltd.co.uk